The present invention relates to an injection device for fluid propellants for guns, with the injection device including a pump chamber to accommodate the propellant, a pump piston axially movable therein and a means for the measured opening and closing of apertures in an injector surface disposed at least partially around a combustion chamber approximately radially to the direction of projectile ejection, and to a fluid propellant gun having at least one of these injection devices.
Such an arrangement is disclosed in German Patent No. 2,226,175 and corresponding U.S. Pat. No. 3,763,739 to Douglas P. Tassie which relates to a valve for controlling the propellant supply into the combustion chamber of an automatic weapon. The weapon here includes a weapon housing in which a barrel having a bore is rigidly fixed. The rear end of the bore is subdivided into chambers so as to accommodate a projectile and to form a combustion chamber whose end opposite the projectile is sealed by a breechblock. The circumferential face of the combustion chamber between the projectile chamber and the breechblock is partially designed as an injector surface. The term "injector surface" is to be understood herein to mean a surface provided with a plurality of apertures (injection nozzles) through which the fluid propellant is injected into a combustion chamber.
A control slide makes it possible, depending on its position, to release the flow cross section of the inlet openings of the injector surface by appropriate parallel displacement.
German Patent No. 1,728,077 discloses a differential pressure piston combustion chamber system for generating propellant gases, particularly for firearms. The propellant and the oxygen or, more precisely, the oxygen carrier, are injected into the combustion chamber axially with respect to the direction of projectile ejection by way of corresponding intake conduits and chambers. The partial quantities of the two propellant components injected into the combustion chamber react hypergolically. With initiation of the combustion process, the pressure in the combustion chamber increases and drives the differential piston back, thus causing further injection of a further quantity of the two propellant components stored in the dosaging chambers.
German Offenlegungsschrift [laid-open patent application] 2,725,925 and corresponding U.S. Pat. No. 4,023,463 to Douglas P. Tassie disclose a pumping device for a gun operated with a liquid propellant. The propellant introduced into a pump chamber is injected axially into the combustion chamber by way of channels disposed in the head section of a pump piston. A displaceable sleeve arranged coaxially with the pump piston has an enlarged head which serves to control the flow and quantity of the propellant.
All of the above prior art arrangements are relatively complicated in their structural design and in the association of the individual components as well as their sequences of movement. A particular drawback, however, is that the supply of propellant can be dosaged only in relatively large quantity steps. Moreover, due to the structural design of arrangements which provide for radial propellant input into the combustion chamber as in German Patent No. 2,226,175 and U.S. Pat. No. 3,763,739, the propellant is supplied only at one end or moves gradually across the cross section of the combustion chamber, so that pressure generation is different throughout the combustion chamber and makes reproducibility of the internal ballistics difficult.
Different guns require different propellant supplies and control possibilities for propellant injection and these can also not be provided by the prior art arrangements. The case is similar with respect to variability of the projectile ejection velocity and temperature influences, for example, as a result of so-called "warming up" of the gun barrel.
Additionally, in some prior art arrangements the introduction of the projectiles is relatively complicated as disclosed, for example, in German Patent No. 1,728,077.
In an arrangement disclosed, for example, in German Patent No. 2,226,175 and corresponding U.S. Pat. No. 3,763,739 there exists an additional drawback in that damping of components sometimes charged with high velocities is possible only conditionally, which sometimes brings about considerable and undesirable excess material stresses, and interferes with the resistance to malfunctions of a gun, particularly during continuous operation.